Background/Purpose: The fingers have specialized structural and functional features for thermoregulation, and are the most common areas of Raynaud’s phenomenon (RP) in systemic sclerosis (SSc). Nailfold videocapillaroscopy (NVC) is the gold standard for quantification of vascular abnormalities in SSc-RP. Digital thermal monitoring (DTM) of vascular reactivity assesses Doppler ultrasound hyperemic, low frequency, blood velocity of radial artery and fingertip vascular function. In this study, we investigated the correlation of NVC patterns and DTM variables in SSc patients.

Methods: Patients enrolled in a single center SSc (2013 ACR/EULAR Classification Criteria) registry who had NVC and DTM performed at a time standard care visit were included in this analysis. The SSc clinical features were recorded. DTM of both hands was obtained during 5 min stabilization, 5 min cuff inflation to 50 mm Hg greater than systolic blood pressure, and 5 min deflation using an automated, operator-independent protocol (VENDYS, Endothelix Inc., Houston, TX). Thermal changes during a 5 min arm-cuff induced reactive hyperemia test were monitored continuously in the fingertip of both the occluded and non-occluded arms using VENDYS software. Dual channel temperature data were simultaneously recorded at a 1 Hz sampling rate. Temperature rebound is defined as temperature prior to cuff inflation subtracted from temperature maximum after cuff relief. Temperature rebound area under the curve is provided as a single value of DTM. Vascular reactivity index (VRI) was calculated on adjusted temperature rebound. NVC was performed to classify the patients into one of the three main patterns of SSc microangiopathy (“early”, “active”, “late”). The following parameters were analyzed in eight fingers of the hands (excluding thumbs): number of capillaries/mm, number of enlarged and giant capillaries, microhemorrhages, and avascular score. Statistical evaluation was performed by non-parametric tests to assess the correlation of NVC and DTM variables.

Results: Thirty-one SSc subjects with interpretable NVC and DTM performed on the same day were included in the study. Thirty subjects were female (91%) and mean age ± SD was 58 ± 12 yrs. Mean duration from first non-RP symptom of SSc was 10.8 ± 8 yrs. VRI was progressively higher in SSc patients with the ‘early’, ‘active’ and ‘late’ NVC patterns of microangiopathy (p< 0.0001, Kruskal-Wallis test). There was a significant negative correlation between VRI and microhemorrhages score (r=-0.363, p=0.044, Spearman’s rank correlation). There was no correlation between VRI and other NVC parameters (data not show).

Conclusion: Correlation of NVC patterns and microhemorrhages parameter with VRI seen in this non-invasive study warrants further research. The lack of complete correlation between functional and morphological microvascular abnormalities, measured by DTM and NVC, suggests each of these tools has a place in the evaluation of microangiopathy aspects in SSc patients and complement each other.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/does-digital-thermal-monitoring-correlate-to-specific-nailfold-videocapillaroscopy-abnormalities/